The invention relates to an in-situ sampling device for monitoring compounds. In particular, the invention relates to a method and device for monitoring of volatile organic compounds in groundwater wells.
Presently, large amounts of time, energy, and money are spent monitoring groundwater, for example monitoring groundwater at remediation sites. In recent years, attempts have been made to develop in-situ samplers that can passively sample volatile organic compounds (VOCs) in groundwater wells. Diffusive vapor samplers with sorbent tube and water samplers, as disclosed in U.S. Pat. Nos. 5,481,927 and 5,804,743, provide passive in-situ methods for monitoring VOCs in groundwater and unsaturated soils (vadose) zones.
The diffusive vapor sampler of U.S. Pat. No. 5,804,743, assigned to the assignee of this invention, comprises a diffusion membrane that has a high permeability rate for organic vapors and is impermeable to water. Upon retrieval from the well, the samples are sent to a laboratory for analysis or analyzed by gas chromatography on site.
Diffusive vapor samplers provide advantages over traditional groundwater sampling methods because these samplers do not need purging of groundwater wells in order to collect representative water samples. Purging can increase project costs because removal of water from each well results in large amounts of contaminated purge water that must be disposed. Moreover, purging potentially confounds analytical results by creating sediments, particulates, and erroneous concentration readings. Although in-situ diffusive vapor samplers promote minimization of wastes, they may not provide yield real-time monitoring of groundwater wells.
Therefore, a need exists for methods to monitor groundwater and remediation processes. Further, a need exists for an in-situ device that can be used to monitor volatile organic compounds (VOCs) continuously in groundwater.